"One of the most important cities in southwestern Somalia, Baidoa, has just been captured from Al-Shebab," Ali said in London, after a Somali army commander earlier announced it had been taken by Ethopian and Somali forces.

Baidoa, 250 kilometres (155 miles) northeast of the capital Mogadishu, is one of the main bases of the Al-Qaeda-allied Shebab, and its capture deals a major blow to the insurgents, who control large parts of southern and central Somalia.

Ali was speaking to reporters at the International Institute for Strategic Studies think-tank in London ahead of a conference hosted by the British government on Thursday on the future of Somalia.

UN chief Ban Ki-moon, US Secretary of State Hillary Clinton and other officials from around the world will attend the meeting, which the British government said was aimed at finding a lasting political solution to Somalia's problems.